Possible Topics:

1. Health:

For this years’ summer student program we are seeking for a talented student that is interested in working closely with our group of physicists, computer scientists, and engineers. The student will work in a pure Unix/Linux-oriented computing environment and will have the task to finalize our previously generated GATE-based simulation model which previous students almost finished. He/she will work with the latest version of GATE and thus will work with todays’ most advanced Monte Carlo simulation framework for clinical PET systems. The main tasks of the student will be:• Finalize the previously developed GATE simulation model• Perform a systematic validation of simulation results in comparison to real PET phantom measurements and find further areas for improving the simulation• Develop command-line and script-based tools to smoothly run a GATE simulation with minimal data preprocessing overhead• Optimize the current methods to convert output data of a simulation into input data for our iterative image reconstruction software. Potentially developing own data conversion tools using C++ would be highly appreciated.All the above tasks will be performed in close collaboration with our scientific team and includes some basic training on PET systems as well as on GATE so that the candidate will learn to work with it and design own simulation models.To fulfil these tasks it would be favourable if the candidate has some basic knowledge of tomographic imaging, the physics of PET or medical physics/imaging in general. In addition, adequate knowledge of numerical programming languages like R or MATLAB, functional programming skills using shell scripts and working in a Linux-oriented environment including extensive work on terminal/console environments would be favourable. If the candidate would have programming capabilities using C/C++ the tasks could be solved more easily. The candidate must have strong abilities in abstract thinking as well as some basic knowledge in nuclear physics, should provide practical skills in using Unix/Linux-based systems and have to be able to suggest own solutions as well as being able to work on these with minor supervision.

Carbon monoxide-releasing molecules (CORM) are promising prodrugs since it has been explored that they can safely store and precisely release CO. Carbon monoxide shows a variety of beneficial effects in mammals, e.g. causes vasodilation, activates ion channels, shows anti-inflammatory, anti-proliferative and anti-apoptotic effects. Consequently, the development of molecules that can release CO in a highly controlled fashion (CORMs) under physiological conditions has therefore become a major field of scientific and medical interest. Considerable research interest has been drawn on light-activated CORMs (photoCORMs) which only release CO upon radiation with certain wavelengths. Nowadays, the challenge lies in the activation of photoCORMs with low energy wavelengths, i.e. preferably visible or near-infrared light rather than using the tissue damaging UV light. Different strategies to tune and modify the absorption profile of CORM’s are known, i.e. extending the conjugation of aromatic ligands, attachment of fluorophores, upconverting nanoparticles. Combined with the beneficial effects of CO with molecular targets, photoCORMs have led to a variety of organometallic compounds in the last few years. So far, very little is known about the anti-cancer activity, especially the interaction of CORMs with cells, both before and after release of CO. This project will encompass a detailed investigation on the anti-cancer behaviour of a light-activated Ruthenium(II)dicarbonyl complex functionalised with a luminescent lanthanide complex and a tumour-targeting peptide. The attached lanthanide complex emits visible light which allows to monitor the biodistribution in vitro. The student’s task is to functionalise the provided Ruthenium(II)CORM-peptide conjugate with a lanthanide complex and investigate the biological activity in healthy and non-healthy cell lines with a suite of techniques. Therefore, the project facilitates synthesis as well as the application of sophisticated equipment (UV/VIS and Fourier-Transform infrared spectroscopy, fluorescence imaging, flow cytometry, confocal microscopy) to probe the uptake, mechanism of action, biodistribution and therapeutic potential of CORMs. The student will be integrated in a multidisciplinary environment working together with chemists, biologists and physicists.

Evaluation of DNA-damage and cell cycle status of xenograft tumors after combined molecular and external radiotherapy

2. Matter:

Measuring the dynamics of the magnetization in nano-structures using magneto-optics.- introduction into magneto-optical Kerr effect and inelastic light scattering for detecting spin waves in ferromagnets- using these optical approaches to determine the resonance frequencies in Nano- and microstructures of various shapes and materials- Comparing the experimental results with micromagnetic simulations and calculations

The summer student will install a new pulsing unit for generating a pulsed ion beam at the new 100kV ion accelerator at the IBC. After successful integration and characterization of the pulsing unit the summer student will perform first Time-of-Flight measurements of back-scattered ions and thus determine efficiency, resolution and calibration of the system. The topic involves a lot of experimental work but less theory. The summer student will be introduced into the basic techniques of ion beam physics and related signal processing hardware.

- Top-down approach for the fabrication of hyperdoped Si nanowires.- Optimization of the flash-lamp annealing conditions, which render the best material quality.- Structural characterization of hyperdoped Si nanowires.- Investigation of the electrical properties by Hall measurements at room and low-temperatures (to inspect the metal-insulator transition)- Electro-optical characterization of the extended IR photoresponse.

The work involves the microcavity ferromagnetic resonance and the electrically-detected ferromagnetic resonance experiments performed on a single and two magnetically coupled nano-stripes, consisting of a ferromagnet-heavy metal (FM/HM) bilayer. The goal of this experimental work is to investigate a synchronization effect of two simple spin-Hall nano-oscillators (i.e., FM/HM stripes) in order to increase their output power and make them suitable for applications as new generation very small and efficient electronic oscillators. The work may be also supplemented by conventional material characterization techniques, such as vibrating sample magnetometry (VSM) or superconducting quantum interference device (SQUID), performed on extended ferromagnetic thin films.

Ferromagnetic resonance measurements on single and multilayer structure under thermal gradient by using microresonator approach.

This summer project focuses on the quantum-mechanical simulations of the interactions between metal-oxide surfaces with radioactive agents, for example, interactions between titania and uranium. This project will be a part of a larger project, in collaboration with another student, who performs kinetic monte-carlo (KMC) simulations, and experimental partners from FWOT HZDR in Leipzig. The density-functional based simulations, which the student will perform during this summer project, will be used as an input for the KMC simulations, in order to understand the reactive transport of, e.g., U on the titania surfaces from theoretical point of view. Furthermore, the theoretical predictions will be complemented by experimental investigations of such reactive transport processes. The student will learn how to work with the simulation software, in this case ADF, BAND, and Crystal, and will perform simulations of the interaction energies between both species. The metal-oxide surface will at first be modelled as smaller clusters. If time allows, the student will extend the simulations to the periodic systems of actual surfaces.

The student will take part in the commissioning experiments of the 5 MV underground ion accelerator in the Dresden Felsenkeller. Specific tasks will be agreed based on the skill set and interests of the summer student. There will be programming tasks (Labview, Python, ROOT/C++), data analysis (gamma-ray spectroscopy), and participation in nuclear physics experiments. -- particular task: Electron screening study (collaboration with JSI Ljubljana as part of the CROSSING project) at HZDR 3 MV Tandetron.

GaN is an attractive material as photocathodes because of its high quantum efficienty and fast response time in UV range. but GaN needed to be actived with cesium atoms to produce negtive electron affinity between the cathode surface and vacuum. the condition of the GaN surface is one of the keys to efficiently active the cathode. During these two monthes, you will be able to join the work in the cleanroom and clean the samples with different chemical processes and physical methods, and analyze the surface with energy dispersive X-ray spectroscopy (EDX) and other devices.

Germanides are of high interest for a couple of applications, especially for contact material, for superconducting materials, for spin injection and for other magnetic applications. Current investigations explore the possibilities to form germanides via the deposition of suitable transition metals on germanium by magnetron sputtering followed by flash lamp annealing. The aim is to investigate and compare the formation of the different germanide phases with focus on contact formation. In the course of these investigations the fabricated samples has to be characterized with respect to their structural, optical and electrical properties. The task of the student would be to handle mainly the part of optical characterization.This includes ellipsometry, transmission, reflectance and Raman measurements.

The student will work with data from X-ray diffraction experiments. This will include comparing the experimental data with known crystal structures, and with simulated data. The student will use software packages for analysis, and would ideally have some familiarity with programming (Python, Matlab or similar), in order to build on the work already performed by the group.

The interaction of high intensity laser and plasma is a nonlinear process and very sensitive to shot-to-shot fluctuation on laser and plasma parameters. This time the task is more on the laser physics than the plasma physics. The summer student will focus on online spectral-temporal measurement of a laser pulse before the interaction. Particullarly, he/she will work on a technique called Frequency-resolved Optical Gating (FROG). The student will build the setup and perform a calibration run and, later, compare the result with other techniques, WIZZLER and Autocorrelator.

My research is primarily focused on probing of dense plasmas with relevance to astrophysics and inertial confinement fusion with various diagnostic techniques, mostly ultra-fast absorption spectroscopy and x-ray Thomson scattering. We also have several projects related to x-ray spectroscopy of metallic samples heated by ultra-short pulse lasers. The student could help with various diagnostic and laser setup in the laboratory, characterization of gas nozzles for laser wakefield acceleration experiments, diagnostic development and data analysis.

- Learn how to run molecular dynamics simulations using the LAMMPS code- Learn how to use various software for the visualization of the atomistic simulations- Scripting for data analysis- Carrying out the simulations aimed at modeling impacts of atomic clusters (metal, inert gas atom clusters) on free-standing and supported graphene and transition metal dichalcogenides

We are interested in measuring electronic transport through different molecules. Themeasurement setup consist of a Mechanically Controlled Break Junction (MCBJ), given bynanoscopic junction which can be controlled with high precision and used to “catch” molecules.By applying voltage bias to the contacts we can probe the properties of the molecule and fit it totheoretical predictions. Work to be performed by the student would consist of learning basic nanotechnologymanufacturing techniques, processing of the measurement samples, and further of using themto measure one of the available molecules (polythiophenes).After that data would be evaluated and plotted with the help of Matlab programing package.

In this project, the summer student will develop new ultra thin targets for laser driven ion acceleration. In particular, have will establish a technique to produce metal film with thicknesses in the ragne of 5µm to a few hundert µm. Additionally, the target thickness has to be determinend with white light interferometry.

Current deep learning frameworks cannot handle complex numbers. However, most image reconstruction algorithms (CT and MRI) use complex numbers. In our work of reducing raw data from CT/MRI scanners without information loss, we have explored auto-encoders, but they introduce undesired artifacts, which might come from the lack of support for complex numbers. Initial work on integrating complex numbers into Tensorflow is also nearly complete. The summer student would work on implementing DL frameworks with complex numbers to compare them against the "classic" networks currently used.

3. Energy:

The summer student will carry out basic research in the area of nuclear waste management, performing experiments in a controlled laboratory, which is not a common facility found at universities. He/she will be mainly focused on the synthesis and characterization of the mineral phase green rust. Eventually, he/she will conduct sorption experiments with the prepared mineral phases with the goal to gain a fundamental understanding of the interactions of 99Tc with the mineral phase. During her/his stay at HZDR, he/she will be trained to handle β-particle emitting materials such as Tc. Additionally, she/he will learn to carry out experiments under inert gas conditions and in glove boxes.Beside common analytical instrumentation (ion chromatography, mass spectrometry, colloidal characterization methods) the controlled laboratories provide access to sophisticated spectroscopic techniques (in situ vibrational spectroscopy, laser-induced fluorescence spectroscopy, diffractometry) as well as to radioanalytics ( α-, β-, γ-spetrometries) and techniques to work under inert gas atmosphere (glove boxes, Schlenck lines). Additionally, access to further microscopic techniques placed in other departments and computational methods is given.The working plan is as follows:(1) Short literature research on the natural formation of green rust and other Fe(II)-minerals, surface and colloidal properties and Tc uptake by such mineral phases.(2) Synthesis of green rust in a glove box under inert gas atmosphere.(3) Characterization of the mineral by different techniques to determine surface area (BET), hydrodynamic diameter (diffusion light scattering), surface charge (laser Doppler electrophoresis) and morphology (atomic force microscopy, scanning electron microscopy, and/or transmission electron microscopy).(4) Batch sorption experiments under N2 conditions to evaluate the retention behavior of 99Tc on green rust. To analyze the amount of 99Tc in solution, liquid scintillation counting will be used.The results will contribute to the preliminar understanding of the mechanisms responsibles of the 99Tc retention.(5) Elaboration of the final presentation.The realization of the tasks mentioned before will be flexible and dependent on the time.Most of the experiments will be carried out in a radiation protection area. Please, be aware that pregnant women are not allowed to work in those laboratories.

Uranyl-peroxo-nanoparticles have been discovered as a synthetic analogue of naturally occurring uranium minerals. More recently, it has become evident that such particles may also form in natural systems, for instance during the dissolution of uranium minerals in the presence of peroxide, a common product of water radiolysis.The student will characterize the interaction of uranyl peroxide nanoparticles with mineral phases relevant to nuclear waste disposal. He will employ time-resolved laser-induced luminescence spectroscopy in combination with atomic force microscopy and ATR-IR spectroscopy to characterize the mode of binding of the particles as a function of geochemical parameters.

The core target would be to design a flexible process to be chosen among these three:- Pressure swing adsorption for air separation.- Water electrolysis for hydrogen and oxygen separation.- Wastewater treatment, with a focus on membrane bioreactors and aeration strategies.It would also be possible for the students to pick another chemical process they are familiar with.

For a given process, students are expected to:- Collect information on the process, its modelling, and its operation with renewable energies.- Model the process in Aspen Plus or Simba #- Simulate a dynamic operation where the electricity comes from renewable sources.